I wonder for such abandoned projects with non existent supply chain/know-how/documentation, whether there is any benefit of trying to revive them instead of starting from scratch.
I almost skipped the videos embedded in this article, but they are well curated gems. A few tidbits I found amazing:
- 800°F (and above) was the temperature of their cooling air
- the engine ran too hot for electronics, so they designed a hydraulic mechanical computer responsible for regulating various inputs
- the roar from the two external 400 cubic inch Buick V8 engines originally used to start the aircraft was so irresistible to the hotrod enthusiasts running them that they sometimes neglected to disconnect in time before the starter engines overran RPM limits and "puked their guts out under the airplane" - they had to buy up so much replacement stock as to deplete every single junkyard across the USA of that particular model (so the story goes - probably hyperbole but a fun tale!)
I remember quite well the day the auctioned off a unique "jet fuel analyzer" that was used to do some of the specialized testing for these exact aircraft.
It was not a benchtop unit, it was a forklift model :\
A handful of the surviving planes are in museums. If you're at all interested in aviation and have the chance to see one, do. There's something special about them that doesn't come across in pictures.
In the 90s, NASA refurbished and extensively modified a mothballed supersonic Soviet-era Tu-144. The modifications included fitting different (Tupolev) engines. The total cost was $350M. It was used as a flying laboratory.
Guessing this project was also a way to pay Russian engineers while the Soviet Union collapsed with the goal to do "technology transfer" and prevent them from working for NK and the like as a way to make ends meet.
Yep. After the collapse of the USSR, the US Congress and NASA funded the International Space Station program in part to keep Russian rocket scientists gainfully employed. That way they wouldn't be tempted to go work for Iraq / Iran / North Korea / China.
When I see this, I can only think of modern high-altitude balloons. My gut tells me the SR-71 would be an ideal interceptor for that new threat (despite not being an interceptor itself).
The balloon issue cannot be addressed by any modern US aircraft, and spending expensive missiles on low cost balloons seems like wasting money and resources.
The SR-71 was never designed as an interceptor, and would require extensive modifications to carry and employ weapons. Not going to happen. There was an earlier YF-12 interceptor program but it never proceeded beyond the prototype stage.
High-altitude balloons are hardly a new threat. They have been used for decades, although some recent Chinese models are more capable than before. Regular tactical aircraft already in the US inventory are perfectly capable of shooting them down.
Current aircraft is not capable of reaching those balloons, read my other commentary. Your link points to a Chinese balloon that dropped way below its operational range.
SR-71 or not, there are already contracts for filling this niche:
If money is flowing to counter/develop high-altitude balloons and declared as urgent, it's likely it's flowing in more than one vein.
The frame modifications you mentioned are already specified and tested, part of the YF-12 programme. It can easily carry air-to-air missiles instead of reconnaissance equipment, and the frame has flown with that configuration.
AIM-120 range and altitude upgrades have been in the works for many years, and balloon defense is a relatively low priority mission. It will also be supplemented by the new AIM-260 which has greater capabilities. The primary goal of those programs is to achieve greater stand-off range versus near-peer adversary aircraft.
The YF-12 prototypes looked superficially similar to the SR-71 but had substantially different airframes. There is simply no place in an SR-71 to mount the necessary weapons, sensors, and avionics without completely rebuilding the entire aircraft. That would be a stupid waste of resources when existing platforms can already accomplish the mission well enough.
The service ceiling of the SR-71 is still well beneath the altitude of a modern balloon. The speed isn't necessary, and it's altitude record has been beaten by other modern jets.
If we're spitballing solutions, balloons are slow, fragile and move in relatively predictable paths. An F-15 could reach the same altitude, and launch it's own balloon with a small solid-fuel booster that also corrects the trajectory. If the interceptor balloon could get within 1-2km of the target balloon, then a cheap kinetic weapon firing HEI projectiles might be enough to destroy it.
That is the lower bound of what modern high-altitude balloons can reach. Back in 2023 multiple balloons were observed much higher than that up to 50,000 feet.
This is still in the lower spectrum for such balloons. BS 13-08 reached 176,000 feet back in 2013 (there is reason to believe spy balloons would not go that high though).
So, you're wrong. There is no US aircraft that can reach them (unless they drop low as they did in 2023). The US likely wants to hit them before they go low.
The SR-71 is uniquely suited for this task, having reached up to 90,000 feet during testing. It was specially made for some kind of hybrid space war possibility (not balloons, but something high up there).
Your amounts are off. that wikipedia page lists the f-15 as having a service ceiling of 65,000 feet. Perhaps irrelevant but a f-15 shot a satellite down once(not relevant because that is more the missiles capabilities than the planes, which is probably the relevant point)
Unit mix up?
The f-16 however, does have a surprisingly low ceiling, there are fighter pilot memes about it. https://www.youtube.com/watch?v=koEQp8ImlnI?t=643 something about having small wings, get above 30,000 feet and it's not happy.
You misread your source: the F-15 can climb 30,000 feet in 60 seconds - the service ceiling is closer to 60,000 feet officially, and 90,000 under ideal conditions:
By "same altitude" I was referring to the SR-71. I do not know what the payload capacity was for either aircraft in the 90,000ft testing conditions, but for interception missions there are more important metrics.
Per the first link you provided, the F-15 has the following:
Service ceiling: 65,000 ft (20,000 m)
That's high enough to go 15k feet above the highest ballon mentioned in the second link you provided, which was 50,000 feet.
Also, the SR-71 carried no weapons, only cameras, and re-tooling to support them would be far more expensive than merely shooting a balloon with a missile from the ground (or building an air-to-air missile that can be fired from existing platforms at altitudes like 65k feet).
I wonder for such abandoned projects with non existent supply chain/know-how/documentation, whether there is any benefit of trying to revive them instead of starting from scratch.
I almost skipped the videos embedded in this article, but they are well curated gems. A few tidbits I found amazing:
- 800°F (and above) was the temperature of their cooling air
- the engine ran too hot for electronics, so they designed a hydraulic mechanical computer responsible for regulating various inputs
- the roar from the two external 400 cubic inch Buick V8 engines originally used to start the aircraft was so irresistible to the hotrod enthusiasts running them that they sometimes neglected to disconnect in time before the starter engines overran RPM limits and "puked their guts out under the airplane" - they had to buy up so much replacement stock as to deplete every single junkyard across the USA of that particular model (so the story goes - probably hyperbole but a fun tale!)
For those that want to know more about the Buick engines and their replacement, here's [0] a writeup about it.
[0] https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...
I remember quite well the day the auctioned off a unique "jet fuel analyzer" that was used to do some of the specialized testing for these exact aircraft.
It was not a benchtop unit, it was a forklift model :\
A handful of the surviving planes are in museums. If you're at all interested in aviation and have the chance to see one, do. There's something special about them that doesn't come across in pictures.
This is probably one of the coolest planes and it's SOP is to leak fuel until it gets going enough that the heat seals it's seams due to expansion
Recent and related:
NASA asked several former SR-71A staffers to help secret restart - https://news.ycombinator.com/item?id=49890733 - Sept 2026 (401 comments)
In the 90s, NASA refurbished and extensively modified a mothballed supersonic Soviet-era Tu-144. The modifications included fitting different (Tupolev) engines. The total cost was $350M. It was used as a flying laboratory.
Guessing this project was also a way to pay Russian engineers while the Soviet Union collapsed with the goal to do "technology transfer" and prevent them from working for NK and the like as a way to make ends meet.
Yep. After the collapse of the USSR, the US Congress and NASA funded the International Space Station program in part to keep Russian rocket scientists gainfully employed. That way they wouldn't be tempted to go work for Iraq / Iran / North Korea / China.
When I see this, I can only think of modern high-altitude balloons. My gut tells me the SR-71 would be an ideal interceptor for that new threat (despite not being an interceptor itself).
The balloon issue cannot be addressed by any modern US aircraft, and spending expensive missiles on low cost balloons seems like wasting money and resources.
We'll know soon.
The SR-71 was never designed as an interceptor, and would require extensive modifications to carry and employ weapons. Not going to happen. There was an earlier YF-12 interceptor program but it never proceeded beyond the prototype stage.
High-altitude balloons are hardly a new threat. They have been used for decades, although some recent Chinese models are more capable than before. Regular tactical aircraft already in the US inventory are perfectly capable of shooting them down.
https://www.af.mil/News/Article-Display/Article/3288579/f-22...
Current aircraft is not capable of reaching those balloons, read my other commentary. Your link points to a Chinese balloon that dropped way below its operational range.
SR-71 or not, there are already contracts for filling this niche:
https://www.war.gov/News/Contracts/Contract/Article/4613098/... (search for "swamp gas").
If money is flowing to counter/develop high-altitude balloons and declared as urgent, it's likely it's flowing in more than one vein.
The frame modifications you mentioned are already specified and tested, part of the YF-12 programme. It can easily carry air-to-air missiles instead of reconnaissance equipment, and the frame has flown with that configuration.
https://en.wikipedia.org/wiki/Lockheed_YF-12
AIM-120 range and altitude upgrades have been in the works for many years, and balloon defense is a relatively low priority mission. It will also be supplemented by the new AIM-260 which has greater capabilities. The primary goal of those programs is to achieve greater stand-off range versus near-peer adversary aircraft.
The YF-12 prototypes looked superficially similar to the SR-71 but had substantially different airframes. There is simply no place in an SR-71 to mount the necessary weapons, sensors, and avionics without completely rebuilding the entire aircraft. That would be a stupid waste of resources when existing platforms can already accomplish the mission well enough.
What are you talking about? The YF-12C was a converted SR-71. It flew exactly as I'm describing. All of this has already been done before.
You might be confusing the YF-12 with the A-12, which is related but a significantly different airframe.
I won't engage in discussing whether balloons are high priority or not. Let the 2023 events and the funding towards those areas speak for themselves.
The service ceiling of the SR-71 is still well beneath the altitude of a modern balloon. The speed isn't necessary, and it's altitude record has been beaten by other modern jets.
If we're spitballing solutions, balloons are slow, fragile and move in relatively predictable paths. An F-15 could reach the same altitude, and launch it's own balloon with a small solid-fuel booster that also corrects the trajectory. If the interceptor balloon could get within 1-2km of the target balloon, then a cheap kinetic weapon firing HEI projectiles might be enough to destroy it.
The F-15 can climb 30,000 feet.
https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15_Eagle
That is the lower bound of what modern high-altitude balloons can reach. Back in 2023 multiple balloons were observed much higher than that up to 50,000 feet.
https://en.wikipedia.org/wiki/List_of_high-altitude_object_e...
This is still in the lower spectrum for such balloons. BS 13-08 reached 176,000 feet back in 2013 (there is reason to believe spy balloons would not go that high though).
https://en.wikipedia.org/wiki/High-altitude_balloon
So, you're wrong. There is no US aircraft that can reach them (unless they drop low as they did in 2023). The US likely wants to hit them before they go low.
The SR-71 is uniquely suited for this task, having reached up to 90,000 feet during testing. It was specially made for some kind of hybrid space war possibility (not balloons, but something high up there).
Your amounts are off. that wikipedia page lists the f-15 as having a service ceiling of 65,000 feet. Perhaps irrelevant but a f-15 shot a satellite down once(not relevant because that is more the missiles capabilities than the planes, which is probably the relevant point)
Unit mix up?
The f-16 however, does have a surprisingly low ceiling, there are fighter pilot memes about it. https://www.youtube.com/watch?v=koEQp8ImlnI?t=643 something about having small wings, get above 30,000 feet and it's not happy.
You misread your source: the F-15 can climb 30,000 feet in 60 seconds - the service ceiling is closer to 60,000 feet officially, and 90,000 under ideal conditions:
https://theaviationgeekclub.com/how-the-f-15-streak-eagle-br...
By "same altitude" I was referring to the SR-71. I do not know what the payload capacity was for either aircraft in the 90,000ft testing conditions, but for interception missions there are more important metrics.
Per the first link you provided, the F-15 has the following:
Service ceiling: 65,000 ft (20,000 m)
That's high enough to go 15k feet above the highest ballon mentioned in the second link you provided, which was 50,000 feet.
Also, the SR-71 carried no weapons, only cameras, and re-tooling to support them would be far more expensive than merely shooting a balloon with a missile from the ground (or building an air-to-air missile that can be fired from existing platforms at altitudes like 65k feet).